Due to the low cost, fast and ease of molding, PDMS has become one of the most popular materials for microfluidics devices, bioMEMS applications. Meanwhile, the integration of different functional
components on to one single chip (or Lab on a Chip) is the dream for many scientists and engineers in the related area. In addition to the
necessary mechanical components for accommodating the reactions, such as pumps, valves, mixers and so on, optical components such as waveguides,
lens, interferers are all desired to be lumped into such a system.

The waveguide for such a system requires the material to have good transparency, and more important, compatibility with the materials and
current fabrication technique. PDMS is the candidate which fits all the requirements. But, for a waveguide to function, refractive index
difference must be fulfilled that is the refractive index of the core material should be higher than the cladding material.

In this thesis, a PDMS waveguide using different mixing ratios of base and curing agent of Sylgard 184 is fabricated. The main aspects of this thesis work includes: (1) Refractive indices of a series of Sylgard 184 PDMS with base to curing agent ratio have been measured. Different mixing ratios of the base and curing agent
mixture were found to have different refractive index which indicates its potential in waveguide application. (2) A prototype of the waveguide with different mixing ratios for the core and cladding part respectively is fabricated. The idea of the realization of this approach is confirmed.